Embodiments of the present invention generally relate to an apparatus and method for use with a controlled gas atmosphere. More particularly, the apparatus and method of the present invention relates to enhancing CO2, N2, and O2 gas control in an incubator.
There are a number of commercial applications that utilize a controlled gas atmosphere enclosure. For example, in the semiconductor industry, gases are injected into an enclosed chamber wherein one of the gases is plasmarized and strikes a target on a chamber lid causing the target""s materials to deposit on a wafer. Other commercial applications include using controlled gases to cultivate biological cultures in an enclosed chamber, such as an incubator.
A conventional incubator is generally rectangular in shape and has up to five insulated walls (top, bottom, left side, right side, and rear). Each wall may have an inner space defined by the inner and outer surfaces of the insulated wall and the inner spaces can be in communication with each other. An insulated front door together with the insulated walls complete the inner chamber of the incubator and the door is typically mounted on hinges on the front side of one of the side walls. The door allows access into the inner chamber where culture plates are placed or removed from the shelves that are provided therein.
It is desirable to maintain optimal conditions inside the incubator in order to promote the desired growth of the cultures and to document the experiment for repeatability by others. In a conventional incubator, gases such as O2, N2, and CO2 are introduced from their respective supply tanks into the chamber depending on the growing conditions desired by the user. Typically, the user sets the CO2 and O2 setpoints and the appropriate gases are added. N2 can be used to purge excess O2 from the incubator when the O2 level in the chamber is too high for the setpoints.
During the operation of the incubator, the gases contained therein can escape by leaking out through gaps in the seals of the door or when the door is opened and closed. Fluctuations in the gas contents of the incubator can damage the samples or alter the experiment data. Thus, it is important to prevent fluctuations of the gas content by monitoring and compensating for the gases that are lost in order to decrease recovery time. The faster the recovery time, the less time the samples are subjected to differing atmospheres. Conventional incubators can provide feed back of the gases that are lost through a compensation system. However, the compensation system is prone to sensor and system latencies. For example, delays in reporting by a sensor can cause the compensation system to overcompensate and inject more gas than necessary, leading to more fluctuations in the incubator and a longer recovery time. Additionally, delays in reporting time by the sensor can cause the compensation system to under compensate leading to possible destruction of the samples due to longer recovery time.
Other conventional compensation systems can make injection decisions based on an ideal physics model of the incubator. By using the ideal physics model, the system and sensor latencies can be removed, however, this system assumes that the user followed the instructions for proper pressure settings, that the gas instrumentation is accurate, and that the gas supply is under a constant pressure. These factors, if not working properly, can cause additional delays in the compensation system of the incubator.
Therefore, there is a need to further enhance rapid gas concentration recovery systems by providing a pressure input for the gas or gases involved rather than assuming a known pressure based on a manual setting of the gas or gases by the user.
The present invention generally relates to a compensation system to allow a faster recovery during enhancement or depletion of an incubation chamber of an incubator. The faster recovery rate will help to ensure optimal conditions in the chamber for optimal growth of the cultures.
In one embodiment of the present invention, a gas compensation apparatus for an enclosed chamber is provided and can include a gas monitor that can monitor the pressure of a gas being injected into the chamber, a gas injection determiner that can determine the amount of the gas that is required during compensation, and at least one gas supply source for supplying at least one gas into the chamber, wherein the gas monitor, the gas injection determiner and the at least one gas supply source can be in communication with each other. The gas monitor can be a transducer and the compensation can be enhancement of the chamber with the at least one gas. The gas compensation can also be depletion with the at least one gas in the chamber. The gas injection determiner can determine the amount of gas via a formula, wherein the formula can be selected from X(t)=V+(X(0)xe2x88x92V)*exe2x88x92(q*t/V) and X(t)=(q*V/(q+q1))+(X(0)xe2x88x92(q*V/(q+q1)))*e (xe2x88x92(q+q1)*t/V). The gas injection determiner can determine the amount of gas via a formula, wherein the formula can be selected from X(t)=X(0)*exe2x88x92(q*t/V) and X(t)=X(0)*e(xe2x88x92(q+q1)*t/V). Additionally, the definition of q and q1 can be selected from [2.90+[(Pxe2x88x9210)*0.79]/5]/60 standard liters/sec, when 10xe2x89xa6Pxe2x89xa615 psig and [3.69=[(Pxe2x88x9215)*2]/15]/60 standard liters/sec, when 15xe2x89xa6Pxe2x89xa630 psig. The definition of q and q, can be selected from [2.90+[(Pxe2x88x9210)* 0.79]/5]/60 standard liters/sec, when 10xe2x89xa6Pxe2x89xa615 psig and [3.69=[(Pxe2x88x9215)*2]/15]/60 standard liters/sec, when 15xe2x89xa6Pxe2x89xa630 psig. The q and q1 can be multiplied by a correction value and the correction value can be selected from CO2=0.808, for O2=0.95, and for N2=1.01. The q and q1 can be multiplied by a correction value and the correction value can be selected from CO2=0.808, for O2=0.95, and for N2=1.01.
In another embodiment of the invention, a method of compensation is provided and can include determining what compensation is need in the chamber, determining the pressure of at least one gas that is injected into the chamber, and injecting the at least one gas into the chamber during compensation. The compensation may be enhancement by injecting at least one gas into the chamber and may be depletion by injecting at least one gas into the chamber. Determining the pressure may be done via a transducer. Injecting the at least one gas can include injection based on a formula selected from X(t)=V+(X(0)xe2x88x92V)*exe2x88x92(q*t/V), X(t)=(q*V/(q+q1))+(X(0)xe2x88x92(q*V/(q+q1)))*e(xe2x88x92(q+q1)*t/V), X(t)=X(0)*exe2x88x92(q*t/V) and X(t)=X(0)*e(xe2x88x92(q+q1)*t/V). The definition of q and q1 can be selected from [2.90+[(Pxe2x88x9210)* 0.79]/5]/60 standard liters/sec, when 10xe2x89xa6Pxe2x89xa615 psig and [3.69=[(Pxe2x88x9215)*2]/15]/60 standard liters/sec, when 15xe2x89xa6Pxe2x89xa630 psig. The q and q1 can be multiplied by a correction value, the correction value can be selected from CO2=0.808, for O2=0.95, and for N2=1.01.
In still another embodiment a compensation system for an enclosed chamber can include means for determining if compensation is needed in the chamber, means for monitoring a pressure of a gas in the chamber, means for determining the amount of at least one gas to inject into the chamber during compensation, and means for injecting the at least one gas, wherein the means for determining, the means for monitoring, the means for determining and the means for injecting can be in communication with each other. The means for determining if compensation is needed can be a controller means. The means for monitoring the pressure can be a transducer means. The means for determining amount of least one gas can be based on a formula selected from X(t)=V+(X(0)xe2x88x92V)*exe2x88x92(q*t/V), X(t)=(q*V/(q+q1))+(X(0)xe2x88x92(q*V/(q+q1)))*e(xe2x88x92(q+q1)*t/V), X(t)=X(0)*exe2x88x92(q*t/V) and X(t)=X(0)*e(xe2x88x92(q+q1)*t/V). The definition of q and q1 can be selected from [2.90+[(Pxe2x88x9210)* 0.79]/5]/60 standard liters/sec, when 10xe2x89xa6Pxe2x89xa615 psig and [3.69=[(Pxe2x88x9215)*2]/15]/60 standard liters/sec, when 15xe2x89xa6Pxe2x89xa630 psig. The q and q1 can be multiplied by a correction value, the correction value can be selected from CO2=0.808, for O2=0.95, and for N2=1.01. The means for injecting the at least one gas can be done by injecting gas from a gas supply tank at a predetermined flow rate and pressure.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.